/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.feilong.lib.net.ftp.parser;

import java.util.Calendar;

import com.feilong.lib.net.ftp.FTPFile;

/**
 * Parser for the Connect Enterprise Unix FTP Server From Sterling Commerce.
 * Here is a sample of the sort of output line this parser processes:
 * "-C--E-----FTP B QUA1I1 18128 41 Aug 12 13:56 QUADTEST"
 * <P>
 * <B>
 * Note: EnterpriseUnixFTPEntryParser can only be instantiated through the
 * DefaultFTPParserFactory by classname. It will not be chosen
 * by the autodetection scheme.
 * </B>
 * 
 * @version $Id$
 * @see com.feilong.lib.net.ftp.FTPFileEntryParser FTPFileEntryParser (for usage instructions)
 * @see com.feilong.lib.net.ftp.parser.DefaultFTPFileEntryParserFactory
 */
public class EnterpriseUnixFTPEntryParser extends RegexFTPFileEntryParserImpl{

    /**
     * months abbreviations looked for by this parser. Also used
     * to determine <b>which</b> month has been matched by the parser.
     */
    private static final String MONTHS = "(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)";

    /**
     * this is the regular expression used by this parser.
     */
    private static final String REGEX  = "(([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z])"
                    + "([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z])([\\-]|[A-Z]))" + "(\\S*)\\s*"      // 12
                    + "(\\S+)\\s*"                                                                             // 13
                    + "(\\S*)\\s*"                                                                             // 14 user
                    + "(\\d*)\\s*"                                                                             // 15 group
                    + "(\\d*)\\s*"                                                                             // 16 filesize
                    + MONTHS                                                                                   // 17 month
                    + "\\s*"                                                                                   // TODO should the space be optional?
                    // TODO \\d* should be \\d? surely ? Otherwise 01111 is allowed
                    + "((?:[012]\\d*)|(?:3[01]))\\s*"                                                          // 18 date [012]\d* or 3[01]
                    + "((\\d\\d\\d\\d)|((?:[01]\\d)|(?:2[0123])):([012345]\\d))\\s"
                    // 20 \d\d\d\d  = year  OR
                    // 21 [01]\d or 2[0123] hour + ':'
                    // 22 [012345]\d = minute
                    + "(\\S*)(\\s*.*)";                                                                        // 23 name

    /**
     * The sole constructor for a EnterpriseUnixFTPEntryParser object.
     *
     */
    public EnterpriseUnixFTPEntryParser(){
        super(REGEX);
    }

    /**
     * Parses a line of a unix FTP server file listing and converts it into a
     * usable format in the form of an <code> FTPFile </code> instance. If
     * the file listing line doesn't describe a file, <code> null </code> is
     * returned, otherwise a <code> FTPFile </code> instance representing the
     * files in the directory is returned.
     *
     * @param entry
     *            A line of text from the file listing
     * @return An FTPFile instance corresponding to the supplied entry
     */
    @Override
    public FTPFile parseFTPEntry(String entry){

        FTPFile file = new FTPFile();
        file.setRawListing(entry);

        if (matches(entry)){
            String usr = group(14);
            String grp = group(15);
            String filesize = group(16);
            String mo = group(17);
            String da = group(18);
            String yr = group(20);
            String hr = group(21);
            String min = group(22);
            String name = group(23);

            file.setType(FTPFile.FILE_TYPE);
            file.setUser(usr);
            file.setGroup(grp);
            try{
                file.setSize(Long.parseLong(filesize));
            }catch (NumberFormatException e){
                // intentionally do nothing
            }

            Calendar cal = Calendar.getInstance();
            cal.set(Calendar.MILLISECOND, 0);
            cal.set(Calendar.SECOND, 0);
            cal.set(Calendar.MINUTE, 0);
            cal.set(Calendar.HOUR_OF_DAY, 0);

            int pos = MONTHS.indexOf(mo);
            int month = pos / 4;
            final int missingUnit; // the first missing unit
            try{

                if (yr != null){
                    // it's a year; there are no hours and minutes
                    cal.set(Calendar.YEAR, Integer.parseInt(yr));
                    missingUnit = Calendar.HOUR_OF_DAY;
                }else{
                    // it must be  hour/minute or we wouldn't have matched
                    missingUnit = Calendar.SECOND;
                    int year = cal.get(Calendar.YEAR);

                    // if the month we're reading is greater than now, it must
                    // be last year
                    if (cal.get(Calendar.MONTH) < month){
                        year--;
                    }
                    cal.set(Calendar.YEAR, year);
                    cal.set(Calendar.HOUR_OF_DAY, Integer.parseInt(hr));
                    cal.set(Calendar.MINUTE, Integer.parseInt(min));
                }
                cal.set(Calendar.MONTH, month);
                cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(da));
                cal.clear(missingUnit);
                file.setTimestamp(cal);
            }catch (NumberFormatException e){
                // do nothing, date will be uninitialized
            }
            file.setName(name);

            return file;
        }
        return null;
    }
}
